Sintered plate electrode with expanded-metal grid



Oct. -20, 1959 P. HAGsPu-u. 2,999,586 SINTERED PLATE`ELECTRODE WITH EXPANDED-METAL GRID Filed Deo. 8, 1952 2 sheets-sheet 1 Oct. 20, 1959 P, HAGsPll-[L v 2,909,586

l SINTERED PLATE ELECTRODE WITH EXPANDED-METAL GRID,

' Filed Deo. 8, 1952 4 2 Sheets-Sheet 2 Fig. 5

United States Patent SINTERED PLATE ELECTRODE WITH EXPANDED-METAL GRID Paul Hagspihl, Hagen, Westphalia, Germany, assignor to Accumulatoren-'Fabrik Aktiengesellschaft, Hagen, Westphalia, Germany, a joint-stock company under German law Application December 8, 1952, Serial No. 324,693 Claims priority, application Germany December 18, 1951 2 Claims. (Cl. 136-28) This invention relates to sntered metal bodies adapted for use as electrodes in alkaline accumulators or storage cells.

It is an object of this invention to improve the mechanical resistivity of such bodies.

As is well known to those skilled in the art, the porous sntered metal bodies serving as carriers for the active mass in alkaline acoumulators are, as a rule, reinforced mechanically by placing them on metal frames or surrounding them with metal Aframes. In addition to this, an electrically conductive, but electrochemically inactive material in the form 4of wires, ribbons, rods, perforated sheets or metal wool, metal chips, metal gauze and the like is forced into the mass and may be connected with it by sintering, and the metal frames or inserts, forming part of a sntered plate electrode may serve as current leads.

I have now found that expanded metal is particularly adapted for use as a skeleton for the active mass and irnparts to the plate very favorable properties. lf thel metal is subject to corrosive attack by the alkaline electrolyte, it should, of course, -be subjected to galvanic or other 'treatment ydesigned to render it inert (electrochemically inactive).

In the drawings aiiixed to this speciiication and forming part thereof some embodiments of the invention are illustrated diagrammatically by way of example.

In the drawings a sntered electrode is shown with an expanded metal grid embedded in the sntered active mass Fig. 1 is an elevation of this electrode,

Fig. Z being la vertical cross-section on the line I--I in Fig. 1.

Fig. 3 shows in cross-section `an electrode in which the expanded-metal grid is embedded altogether in the sintered Aactive mass.

Fig. 4 is another embodiment showing two such skeletons embedded in the mass, and

Fig. 5 shows the expanded-metal grid made in one piece with the contact lug.

Referring to the drawings and rst to Figs. 1 and 2, 1 is a metal fra-me and 2 is the contact lug. 3 is an expanded metal grid and 4 are leads connecting same to the frame 1. 5 is the sntered active mass enveloping the grid and the two surfaces of the frame.

In Fig. 3 a large expanded-metal grid -6 yis embedded Ialtogether in the sntered active mass 7, and in Fig. 4 `an electrode of greater thickness is shown as having two expanded metal grids 8 4and 9 embedded in the sntered active mass 10.

Fig. 5 shows an expanded-metal grid 11 formed from ICC the metal of the frame 12 and of the contact lug 13.

It is obvious that in view of the particular advantages offered by the expanded metal, in whose production no metal is wasted, the elasticity and mechanical strength 5 characteristic of expanded metal sheets is imparted also to the sntered plate itself. Owing to the subdivision of the sntered `cake by the grid into a great number of parallel sections the forces generated by the shrinking of the mass during sintering are also subdivided and are not sufficiently strong to disrupt the cake which is thus free from -any cracks.

Since the cake does not undergo any considerable shrinking, its porosity becomes greater than that of the sntered cakes hitherto produced and its mechanical 15 .strength is not reduced. The complete and uniform penetration ofthe sntered structure with a current-conductive insert and the large contact surface with the sntered body contributes to a particularly favorable entrance and exit of the current.

The higher porosity of the sntered body renders it possible to better and more uniformly 4impregnate the ,plate with active mass and leads to an increase of the mass absorbed.

Since the webs of the expanded-metal sheet extend sub` stantially at right angles to the plane of the sheet, the ,=mass is not rendered inaccessible on one side and therefore can participate throughout their depth from one to the other surface in the electrochemical reactions.

If the expanded-metal body is used without a frame,

it will be provided with the necessary current leads. The contact lug can be made out of the expanded-metal body.

By distending this body so as to distort the rhombic perforations, one can vary the degree of elasticity of the grid, so that the sntered cake is able to give way or revsist to the shrinking forces arising during the sintering [and to the expanding tendency developing during operjation of the accumulator.

I wish it to be understood that I do not desire to be limited to the details described in the foregoing specifi- 'cation and shown in the drawings for obvious modifications will occur to a person skilled in the art.

I claim:

1. A sntered metal electrode for alkaline laccumulators of increased electric efliciency,.said electrode having a ,grid of expanded metal embedded in the sntered metal whereby the porosity of the sntered body is increased be- -cause of reduced sintering shrinkage and the receptivity of the sntered body for active material is correspondingly improved.

2. A sntered metal electrode for alkaline accumu- A lators of increased electric eiciency comprising a mass of sntered metal, a metal frame surrounding said sntered mass, and a grid of expanded metal embedded in the sintered mass and electrically connected to said frame, said grid dilering from said sntered mass and being electrochemically inert.

References Cited in the le of this patent UNITED STATES PATENTS 664,438 Sargent Dec. 25, 1900 1,918,947 Williams July 18, 1933 1,982,485 Salmon et al Nov. 27, 1934 2,251,913 Brennan Aug. 12, 1941 2,544,112 schneider Mar. 6, 1951 2,672,494 Fleischer Mar. 16, 1954 

1.A SINTERED METAL ELECTRODE FOR ALKALINE ACCUMULATORS OF INCREASED ELECTRIC EFFICIENCY, SAID ELECTRODE HAVING A GRID OF EXPANDED METAL EMBEDDED IN THE SINTERED METAL WHEREBY THE POROSITY OF THE SINTERED BODY IS INCREASED BECAUSE OF REDUCED SINTERING SHRINKAGE AND THE RECEPTIVITY 